Musannaf Ibn Abi Shayba 27:167

'Isa ibn Yunus narrated to us, from 'Amr, the freed slave of Ghafrah, who said: Ibrahim ibn Muhammad, from the descendants of 'Ali, narrated to us, saying: When 'Ali would describe the Messenger of Allah (may Allah bless him and grant him peace), he would say: He was not excessively tall, nor was he short and squat. He was of medium stature among the people. He had curly hair, but it was neither tightly coiled nor completely straight; it was wavy. He was not fleshy or round-faced, but there was a roundness in his face. He was white, tinged with redness. He had deep black eyes and long eyelashes. He had large joints and shoulders. He was hairless [on his body], except for a thin line of hair [from his chest to his navel]. He had thick palms and feet. When he walked, he would lean forward as if he were walking down a slope. When he turned, he turned with his whole body. Between his shoulders was the Seal of Prophethood, and he is the Seal of the Prophets. He was the most generous of people in his palms, the most courageous of people in his chest, the most truthful of people in speech, the most fulfilling of people in his promises, the gentlest of them in temperament, and the noblest of them in companionship. Whoever saw him suddenly would be awestruck by him, and whoever associated with him in familiarity would love him. The one describing him would say: "I have not seen the likes of him, neither before him nor after him."